The present invention relates to Buck regulators. In particular, the present invention relates to a method and apparatus that provides for a Buck regulator with a reduced open-switch voltage requirement.
A buck regulator is a type of step-down switching regulator. A buck regulator provides a regulated DC output voltage to a load. Switching of the regulator is often accomplished with a semiconductor switch. The buck regulator employs an inductor that is arranged to charge when the semiconductor switch is closed. The current through the inductor increases linearly while the semiconductor switch is closed. A capacitor is connected across the load to reduce ripple in the output voltage. A freewheeling diode is connected to the inductor so that current continues to flow through the inductor when the semiconductor switch is opened. The current through the inductor decreases while the semiconductor switch is open. The load, the freewheeling diode, and the capacitor are all connected to a common ground potential.
The present invention is directed to a Buck regulator that includes a semiconductor switching circuit with reduced voltage requirements. The buck regulator includes a transformer with a primary coil that is charged by an input voltage when the semiconductor switching circuit is in a closed circuit condition. A secondary coil of the transformer is arranged to provide an auxiliary regulated potential that may be coupled to an auxiliary load. The auxiliary regulated potential is further arranged to operate as a virtual ground node with respect to the semiconductor switching circuit such that the open circuit voltage requirements for the semiconductor switching circuit are reduced. The open circuit voltage across the semiconductor switching circuit corresponds to the difference between the input voltage and the voltage associated with the virtual ground node.
A more complete appreciation of the present invention and its improvements can be obtained by reference to the accompanying drawings, which are briefly summarized below, to the following detailed description of illustrative embodiments of the invention, and to the appended claims.